GB1558553A - Calcium-selective electrode - Google Patents
Calcium-selective electrode Download PDFInfo
- Publication number
- GB1558553A GB1558553A GB1117278A GB1117278A GB1558553A GB 1558553 A GB1558553 A GB 1558553A GB 1117278 A GB1117278 A GB 1117278A GB 1117278 A GB1117278 A GB 1117278A GB 1558553 A GB1558553 A GB 1558553A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electrode
- selective
- electrode according
- calcium
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000011575 calcium Substances 0.000 title claims description 17
- 229910052791 calcium Inorganic materials 0.000 title claims description 15
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims description 13
- 239000012528 membrane Substances 0.000 claims description 23
- 150000002500 ions Chemical class 0.000 claims description 22
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 18
- 150000001875 compounds Chemical class 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 12
- 239000011521 glass Substances 0.000 claims description 10
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 claims description 8
- 229910052697 platinum Inorganic materials 0.000 claims description 8
- 229920000642 polymer Polymers 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 239000002904 solvent Substances 0.000 claims description 7
- 239000003822 epoxy resin Substances 0.000 claims description 4
- 229920000647 polyepoxide Polymers 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- 238000005227 gel permeation chromatography Methods 0.000 claims description 3
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 3
- 239000004800 polyvinyl chloride Substances 0.000 claims description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 150000001669 calcium Chemical class 0.000 claims description 2
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 2
- 239000001110 calcium chloride Substances 0.000 claims description 2
- 230000001143 conditioned effect Effects 0.000 claims description 2
- 239000004020 conductor Substances 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000010949 copper Substances 0.000 claims description 2
- 125000002243 cyclohexanonyl group Chemical group *C1(*)C(=O)C(*)(*)C(*)(*)C(*)(*)C1(*)* 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims description 2
- 229910001651 emery Inorganic materials 0.000 claims description 2
- 239000000945 filler Substances 0.000 claims description 2
- 238000009413 insulation Methods 0.000 claims description 2
- 230000002452 interceptive effect Effects 0.000 claims description 2
- 238000004382 potting Methods 0.000 claims description 2
- 229920005989 resin Polymers 0.000 claims description 2
- 239000011347 resin Substances 0.000 claims description 2
- 238000012216 screening Methods 0.000 claims description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 10
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 6
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 5
- 239000011324 bead Substances 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 240000008042 Zea mays Species 0.000 description 1
- 235000016383 Zea mays subsp huehuetenangensis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 125000002603 chloroethyl group Chemical group [H]C([*])([H])C([H])([H])Cl 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000004508 fractional distillation Methods 0.000 description 1
- 235000009973 maize Nutrition 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- -1 siloxanes Chemical class 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
- G01N27/3335—Ion-selective electrodes or membranes the membrane containing at least one organic component
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Description
(54) CALCIUM-SELECTIVE ELECTRODE
(71) We, NATIONAL RESEARCH
DEVELOPMENT CORPORATION, a
British corporation established by statute, of Kingsgate House, 66-74 Victoria Street,
London S.W.1., do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment:- This invention relates to a calciumselective electrode, and includes a method of making it and extends to the use of it.
According to the invention, a calciumselective electrode has an electrically conductive member in contact with an ionselective membrane (preferably from 0.01 to 0.3mm thick) comprising the cyclosilox maize compound ((CH;)2SiO)l2, of which up to one CH3 group on each silicon may be substituted. The electrically conductive member may be of platinum. and is preferably in the form of a sheet. The sheet may close one end of a non-conductive tube thrpugh which passes a wire electrically contacting the sheet. Optionally, a conductive screen may surround the tube (but not the sheet), and the electrode may further comprise an outer non-conductive tube surrounding the screen, such that the exterior surface of the electrode presents only said outer tube and said ion-selective membrane.
The ion-selective membrane preferably also comprises a film-forming polymer such as polyvinylchloride, which may account for 10% to 50% (e.g. 30%) by weight of the ion-selective membrane. The ion-selective membrane may be formed by applying to the (preferably abraded) sheet a solution (in a volatile solvent (e.g. cyclohexanone)) of the cyclosiloxane compound and of any film-forming polymer. The solvent may account for 70% to 95% by volume of the solution.
The cyclosiloxane compound may be made as described in UK Patent Specification 1162075, the resulting mixture of siloxanes being separated from the desired twelve-member cyclosiloxane compound by any desired method. Up to one methyl group on each silicon can be substituted, for example being ethyl, chloroethyl, propyl or viny. Conventional methods include molecular sieve techniques and gas chromatography, but the most successful method appears to be gel chromatography.
The invention will now be described by way of example with reference to the accompanying drawing, which shows schematically a sectional elevation of an electrode according to the invention.
Using the method described in UK Patent
No. 1162075, a mixture of cyclosiloxanes was obtained. The mixture was separated using tetrahydrofuran as solvent and a gel permeation material of molecular weight exclusion limit of 1400. This material is a dry powder commercially available as Bio-beads
SX2 consisting of styrene/divinylbenzene copolymer beads which are pre-swollen for 4 hours with tetrahydrofuran to form a homogeneous gel, and rinsed for 8 hours with tetrahydrofuran. A solution of 5g of siloxane mixture in 10ml of tetrahydrofuran was run into the top of a column 2.5m high by 50mm diameter of the Bio-beads, eluted with tetrahydrofuran at the rate of 100 ml/hour. and after about 1 - 2 hours the separated cyclosiloxanes emerged.The desired twelve-membered cyclosiloxane compound ((CH3)2SiO)12 was isolated in a yield as high as 15%, which exceeds the yield obtained by gas chromatography, fractional distillation and other techniques, and is believed to be 95% of all the twelvemembered compound in the cyclosiloxane mixture. The cyclosiloxane is now put aside.
A copper wire 2, for attachment at its upper (free) end to desired electrical apparatus. is soldered in contact with a platinum sheet in the form of a plate 4 (through an intermediate platinum wire 2a). The plate 4 is lmm thick and Smm in diameter, and closes the lower end of a glass tube 6 through which the wire 2 passes.
For protection from interference, the tube 6 is surrounded by a copper screen 8, which itself is surrounded by an outer glass tube 10. The tubes 6 and 10 are sealed together at the bottom. The screen 8 is held in position by an annular filler 12 of an epoxy resin. The plate 4 is heat-sealed into the glass.
At the upper end of the outer tube 10, a similar resin 14 holds the screen 8 and inner tube 6. The screen 8 is electrically connected by turns of wire 15 to the screening of a coaxial-screened cable 16, and the wire 2 is soldered at 18 to the central conductor of the cable 16. Insulation and rigidity are assured by potting with an epoxy resin 20, the whole assembly at the upper end of the outer tube 10 being protected by a rubber cap 22.
Returning to the lower end of the outer tube 10, all that is presented externally is the glass tube 10 and the plate 4. To render this calcium-selective, the plate 4 and surrounding glass are lightly abraded with emery paper and dipped in a solution consisting of 90 parts (by weight) of cyclohexanone. 3 parts of polyvinylchloride and 7 parts of the cyclosiloxane ((CH3)2SiO)l2 prepared as described earlier. Upon being allowed to dry, an ion-selective layer in the form of a membrane 24 which may be 0.01 to 0.3mm thick forms an intimate contact with the platinum plate 4. This membrane is allowed to dry out thoroughly, for 24 hours, and is then conditioned, to make it ready for use, by holding for 24 hours in a centimolar aqueous solution of calcium chloride.
The resulting assembly forms a robust calcium-selective electrode with mechanically sound membrane/platinum contact.
Over a range of conditions. the electrode is highly selective towards calcium. whose concentration it can with reasonable accuracy monitor throughout the range 10 to 10-5M, with a response linear to log (CaT: concentration) in the range 4 x 10-2M to S x 10-5M. The response time depends on concentration and on any interfering ions present, but is generally less than 10 seconds.
The electrode remains selective towards calcium down to pH 1.6. From pH 1.6 to 4.5, response is independent of pH. From 4.5 to 12 there is a pH-dependent decrease in response but, at any given pH up to 9.
response to Ca+ ions is Nernstian.
WHAT WE CLAIM IS:
1. A calcium-selective electrode having an electrically conductive member in contact with an ion-selective membrane comprising the cyclosiloxane compound ((CH3)2SiO)l2 of which up to one CH3 group on each silicon may be substituted.
2. An electrode according to claim 1, wherein the electrically conductive member is of platinum.
3. An electrode according to claim 1 or 2, wherein the electrically conductive member is in the form of a sheet.
4. An electrode according to claim 3, further comprising a non-conductive tube closed at one end by the sheet, through which tube there passes a wire electrically contacting the sheet.
5. An electrode according to claim 4, further comprising a conductive screen surrounding the tube.
6. An electrode according to claim 5, further comprising a non-conductive outer tube surrounding the screen, such that the exterior surfaces of the electrode presents only said outer tube and said ion-selective membrane.
7. An electrode according to any preceding claim, wherein the ion-selective membrane has a thickness of up to 0.3mm.
8. An electrode according to any preceding claim, wherein the ion-selective membrane has a thickness of at least O.Olmm.
9. An electrode according to any preceding claim, wherein the ion-selective membrane also comprises a film-forming polymer.
10. An electrode according to claim 9, wherein the film-forming polymer accounts for 10 to 50% by weight of the ion-selective membrane.
11. A calcium-selective electrode substantially as hereinbefore described with reference to and as shown in the accompanying drawing.
12. A method of making an electrode according to any preceding claim, comprises ing dipping the electrically conductive member in a solution containing the said cyclosiloxane compound, and allowing the dipped member to drv.
13. A method according to claim 12, wherein the solution comprises from 70 to 95% by weight of a solvent for the cyclosilo xane compound.
14. A method according to claim 13, wherein the solvent is cyclohexanone.
15. A method according to claim 12. 13 or 14. wherein the solution further contains a film-forming polymer.
16. A method of making an electrode according to any of claims 1 to 11, wherein said cyclosiloxane compound was isolated from a mixture of cvclosiloxane compounds by gel chromatography.
17. A method of making an electrode according to any of claims 1 to 11, the method being substantially as hereinbefore described.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (19)
1. A calcium-selective electrode having an electrically conductive member in contact with an ion-selective membrane comprising the cyclosiloxane compound ((CH3)2SiO)l2 of which up to one CH3 group on each silicon may be substituted.
2. An electrode according to claim 1, wherein the electrically conductive member is of platinum.
3. An electrode according to claim 1 or 2, wherein the electrically conductive member is in the form of a sheet.
4. An electrode according to claim 3, further comprising a non-conductive tube closed at one end by the sheet, through which tube there passes a wire electrically contacting the sheet.
5. An electrode according to claim 4, further comprising a conductive screen surrounding the tube.
6. An electrode according to claim 5, further comprising a non-conductive outer tube surrounding the screen, such that the exterior surfaces of the electrode presents only said outer tube and said ion-selective membrane.
7. An electrode according to any preceding claim, wherein the ion-selective membrane has a thickness of up to 0.3mm.
8. An electrode according to any preceding claim, wherein the ion-selective membrane has a thickness of at least O.Olmm.
9. An electrode according to any preceding claim, wherein the ion-selective membrane also comprises a film-forming polymer.
10. An electrode according to claim 9, wherein the film-forming polymer accounts for 10 to 50% by weight of the ion-selective membrane.
11. A calcium-selective electrode substantially as hereinbefore described with reference to and as shown in the accompanying drawing.
12. A method of making an electrode according to any preceding claim, comprises ing dipping the electrically conductive member in a solution containing the said cyclosiloxane compound, and allowing the dipped member to drv.
13. A method according to claim 12, wherein the solution comprises from 70 to 95% by weight of a solvent for the cyclosilo xane compound.
14. A method according to claim 13, wherein the solvent is cyclohexanone.
15. A method according to claim 12. 13 or 14. wherein the solution further contains a film-forming polymer.
16. A method of making an electrode according to any of claims 1 to 11, wherein said cyclosiloxane compound was isolated from a mixture of cvclosiloxane compounds by gel chromatography.
17. A method of making an electrode according to any of claims 1 to 11, the method being substantially as hereinbefore described.
18. A calcium-selective electrode made
by a method according to any of claims 12 to 17.
19. A method of determining calcium in a solution, comprising using an electrode according to any of claims 1 to 11 or 18.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1117278A GB1558553A (en) | 1978-03-21 | 1978-03-21 | Calcium-selective electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1117278A GB1558553A (en) | 1978-03-21 | 1978-03-21 | Calcium-selective electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1558553A true GB1558553A (en) | 1980-01-03 |
Family
ID=9981347
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1117278A Expired GB1558553A (en) | 1978-03-21 | 1978-03-21 | Calcium-selective electrode |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1558553A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4388165A (en) * | 1981-02-28 | 1983-06-14 | Olympus Optical Company Ltd. | Selective ion sensitive electrode and method of making it |
| US4388167A (en) * | 1981-09-07 | 1983-06-14 | Olympus Optical Company Limited | Ion selective electrode |
| DE3230147A1 (en) * | 1982-08-13 | 1984-02-16 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Ion-sensitive layer |
| EP0157434A1 (en) * | 1984-02-29 | 1985-10-09 | Nihon Parkerizing Co., Ltd. | Process for regulating the zinc and/or nickel content in phosphatizing solutions |
-
1978
- 1978-03-21 GB GB1117278A patent/GB1558553A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4388165A (en) * | 1981-02-28 | 1983-06-14 | Olympus Optical Company Ltd. | Selective ion sensitive electrode and method of making it |
| US4388167A (en) * | 1981-09-07 | 1983-06-14 | Olympus Optical Company Limited | Ion selective electrode |
| DE3230147A1 (en) * | 1982-08-13 | 1984-02-16 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Ion-sensitive layer |
| EP0157434A1 (en) * | 1984-02-29 | 1985-10-09 | Nihon Parkerizing Co., Ltd. | Process for regulating the zinc and/or nickel content in phosphatizing solutions |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |